The French pronunciation of Oriane is "ori-AHN". I think it's a pretty name and I wouldn't change the spelling to Orianne. I like Oriana too. In medieval legend, Oriana was the daughter of a king of England who married the knight Amadis. If you think you'll have a fair-haired child, this "golden" name would be a subtle way to get to this colour. Of course, she doesn't have to be blond for you to choose it! The name makes me think of the lovely Beatles song, "Golden Slumbers".